Preparation of Chiral-Bridged Dienes - Ligands for Enantioselective Catalysis

Significance

Chiral bicyclic dienes can serve as useful ligands for a number of enantioselective C-C bond formation reactions. Most of these compounds are prepared via a resolution approach or from chiral pool precursors. The authors report a facile enantioselective route towards norbornadiene and bicyclooctadiene ligands using a Diels-Alder reaction catalyzed by 1. Ligands 2 and 3 were shown to be the optimum for the rhodium-catalyzed additions of boronic acids to α,β-unsaturated ketones, leading to the corresponding products with excellent enantioselectivities. In this paper the authors introduce the concept of ‘catalytic pool’ of chiral molecules available by the means of asymmetric catalysis, analogous to the ‘chiral pool’ of natural chiral products.